Method and System for Ladar Pulse Deconfliction to Detect and Track Other Ladar Systems

• US 20180239001A1
• Filed: 02/14/2018
• Published: 08/23/2018
• Est. Priority Date: 02/17/2017
• Status: Active Grant

• Current Assignee: AEye, Inc.
• Original Assignee: AEye, Inc.
• Inventors: Dussan, Luis Carlos, Steinhardt, Allan
• Granted Patent: US 10,209,349 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 17/06 Systems determining position data of a target
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2013/9316 combined with communication equipment with other vehicles or with base stations
• CPC Class Codes: G01S 7/006 using shared front-end circuitry, e.g. antennas G01S13/765, G01S13/825 take precedence
• CPC Class Codes: G01S 7/4816 of receivers alone
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4861 Circuits for detection, sampling, integration or read-out
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/4873 by deriving and controlling a threshold value
• CPC Class Codes: G01S 7/4876 by removing unwanted signals G01S7/495 takes precedence

Abstract

Disclosed herein are a number of example embodiments that employ controllable delays between successive ladar pulses in order to discriminate between “own” ladar pulse reflections and “interfering” ladar pulses reflections by a receiver. Example embodiments include designs where a sparse delay sum circuit is used at the receiver and where a funnel filter is used at the receiver. Also, disclosed are techniques for selecting codes to use for the controllable delays as well as techniques for identifying and tracking interfering ladar pulses and their corresponding delay codes. The use of a ladar system with pulse deconfliction is also disclosed as part of an optical data communication system.

Claims

1. A method comprising:

processing incoming light based on a delay code to classify portions of the incoming light as containing a reflection of an own ladar signal from an own ladar system or corresponding to interference, wherein the own ladar signal comprises a plurality of ladar pulses separated by a delay value corresponding the delay code, and wherein the interference comprises a plurality of interfering ladar signals corresponding to ladar pulses and reflections thereof from one or more other ladar systems that are separated by different delay values corresponding to different delay codes;

detecting the interfering ladar signals in response to the processing;

extracting the different delay codes from the detected interfering ladar signals; and

storing the extracted different delay codes.

2. The method of claim 1 further comprising:

tracking one or more other ladar systems based on the extracted different delay codes.

3. The method of claim 1 wherein the extracting step comprises applying the detected interfering ladar signals to a plurality of sparse delay sum circuits that use different delay values for detecting ladar pulses separated by the different delay values.

4. The method of claim 3 wherein the processing step comprises processing the incoming light through a sparse delay sum circuit that uses the delay value corresponding to the delay code to detect the own ladar signal.

5. The method of claim 4 further comprising:

classifying interfering ladar signals sharing the same different delay code between direct interfering ladar signals and echo interfering ladar signals for the same different delay code based on comparative magnitudes of the interfering ladar signals sharing the same different delay code such the larger magnitude is classified as the direct interfering ladar signal and the smaller magnitude is classified as the echo interfering ladar signal;

determining a time delay between the classified direct interfering ladar signal and the classified echo interfering ladar signal; and

tracking a location for the other ladar system that produced the classified direct interfering ladar signal and the classified echo interfering ladar signal based on the determined time delay.

6. The method of claim 5 further comprising repeating the method steps with respect to interfering ladar signals from a plurality of different other ladar systems;

and

generating a multi-static point cloud based on the tracked locations for the other ladar systems.

7. A system comprising:

a pulse deconfliction circuit configured to process incoming light based on a delay code to classify portions of the incoming light as containing a reflection of an own ladar signal from an own ladar system or corresponding to interference, wherein the own ladar signal comprises a plurality of ladar pulses separated by a delay value corresponding the delay code, and wherein the interference comprises a plurality of interfering ladar signals corresponding to ladar pulses and reflections thereof from one or more other ladar systems that are separated by different delay values corresponding to different delay codes; and

a processor configured to (1) detect the interfering ladar signals based on classifications by the pulse deconfliction circuit, (2) extract the different delay codes from the detected interfering ladar signals, and (3) store the extracted different delay codes in memory.

8. The system of claim 7 wherein the processor is further configured to track one or more other ladar systems based on the extracted different delay codes.

9. The system of claim 7 wherein the processor comprises a plurality of sparse delay circuits that use different delay values for detecting ladar pulses separated by the different delay values, and wherein the processor is further configured to apply the detected interfering ladar signals to the sparse delay sum circuits.

10. The system of claim 9 wherein the pulse deconfliction circuit comprises another sparse delay sum circuit that uses the delay value corresponding to the delay code to detect the own ladar signal.

11. The system of claim 10 wherein the processor is further configured to:

classify interfering ladar signals sharing the same different delay code between direct interfering ladar signals and echo interfering ladar signals for the same different delay code based on comparative magnitudes of the interfering ladar signals sharing the same different delay code such the larger magnitude is classified as the direct interfering ladar signal and the smaller magnitude is classified as the echo interfering ladar signal;

determine a time delay between the classified direct interfering ladar signal and the classified echo interfering ladar signal; and

track a location for the other ladar system that produced the classified direct interfering ladar signal and the classified echo interfering ladar signal based on the determined time delay.

12. The system of claim 11 wherein the pulse deconfliction circuit and the processor are configured to repeat their operations with respect to interfering ladar signals from a plurality of different other ladar systems;

and

wherein the processor is further configured to generate a multi-static point cloud based on the tracked locations for the other ladar systems.